1. Field of the Invention
The present invention pertains to the cleaning of multiple nozzle dispense heads, individual dispense valves and other equipment used to dispense a flowable medium.
2. Description of the Related Art
Dispensing equipment of the type contemplated herein typically includes a nozzle or dispense port from which a flowable medium emerges to enter into a receptacle. Viscous fluids, for example, tend to accumulate at the exterior surface of the nozzle after a dispense operation is completed. It may be desirable for reasons of cleanliness, sanitation or metering accuracy, to remove such residue, and accordingly several arrangements have been proposed to meet this need. For example, commonly owned German patent application P 43 31 924.6 proposes a generally cylindrical cleaning brush mounted for rotation on a horizontal axis within a vessel of cleaning fluid. The vessel is mounted for movement underneath a dispense nozzle. The brush is powered so as to rotate, cleaning the dispense nozzle by mechanical action of its bristles, and by bringing cleaning fluid to the surface of the dispense head as the brush rotates.
The medium being dispensed may vary widely in its characteristics. For example, a medium containing little or no pigment, such as a varnish, may be cleaned in a relatively easy manner. However, paints and other coatings which are heavily loaded with pigment materials may require considerably greater effort and corresponding increased quantities of cleaning fluids to successfully complete a cleaning operation. At times, dispense valves are employed to meter paint tints which are becoming increasingly concentrated over time, to provide a maximum amount of tinting ability in a minimum volume of tint material. Accordingly, it can be expected that a greater quantity of cleaning material would be required to remove such concentrated tinting materials. Perhaps an even greater challenge arises when dispense nozzles deliver highly viscous pasty materials in the form of offset printing inks. At times, such materials have been known to hang in substantial quantities from the underside of a dispense nozzle. The difficult flow characteristics of these materials is further aggravated by the amount of grit they contain. A brush, or other mechanical cleaning media, when brought in contact with such materials, quickly becomes fouled and action must be quickly taken to resolve the situation, before the materials harden.